Apparatus for electric welding



*'(No Model.) A 2 Sheets-Sheet '1. H. LEMP` APPARATUS FOR ELECTRIC WELDING. No. 553,923. Patented Feb. 4, 1896.

INVEINFT'EIH 2 shets-'sheen 2.

(No Model.)

H. LEMP. APPARATUS PoE ELECTRIC WELDING.

Patented Peb. 4, 1896.

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WITNEIEEEEI UNITED STATES PATENT OEEICE.

HERMANN LEMP, OF LYNN, MASSACHUSETTS, ASSIGXOR 'lO 'lIIE THOMSON ELECTRIC lVELDING COllIPANY, OF MAINE.

APPARATUS FOB ELECTRIC WELDING.

SPECIFICATION forming part of Letters Patent NO. 553,923, dated February 4, 1896. i Application filed J' une 17, 1891. Serial No. $96,547. (No model.)

To aZZ whom it may concern.'

Be it known that I, HERMA-NN LEM?, a citizen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, haveinvented certain new and useful Improvements in Apparatus for Electric lYelding, of which the following is a specification.

My invention relates to those electric meta-l- 1o working operations in which one or more pieces of metal are heated by means of the electric current.

The object of my invention is to provide for a more thorough and uniform heating of the work in the operation; and the invention consists in applying to the metal heating electric currents of different frequencyv during the manipulation thereof, and the invention consists in the combination, arrangement and zo operation of parts as hereinafter fully described and. set forth in the claim.

My invention is especially applicable to a metal-working operation consisting in the forming of long joints between strips, plates,

bars or rods-such as boiler-plates or other articles which are at present riveted-by a welding, soldering, cementing or similar operation, though it is likewise applicable to the simple shaping, rolling or forming of a 3o metal rod, bar or strip fed between the forming pressure devices.

I shall hereinafter describe my invention more particularly as applied to the formation of joints between long strips, bars or plates.

3 5 In carrying out my invention the heatingcurrents applied to the work may be two independent currents passed through the strips to be joined one in a direction parallel to the joint and one transversely or at right angles 4o to the joint, or nearly so. Such transverse current might be one made to pass through .or across the pieces diagonally, as the result of two independent alternating currents interfering for displaced in phase. 4 5 I include in my invention bythe terln transversely a'current passed diagonally aswell as at right angles through the metal'piece. The two heating-currents may be passed through the same portion of the one or more v5o strips, plates or rods at the same time or they may be entirely distinct and sent through one after the other. The heating-currents might be passed through. a portion of the work longitudinally, which is some distance removed from the pressure devices and the cur- 5 5 rent passed through such portion transversely only after it has reached the pressure devices.

In carrying out my invention I prefer to employ two distinct sources of energy supplying current to the work. 6o

In t-he accompanying drawings, Figure l illustrates in plan an apparatus that. might be used for the purpose of uniting plates, strips, or bars of metal and heating the same .in the manner employed previous to my in-V vention. Fig. 2 is an end View of the same. Fig. 3 illustrates an 'apparatus that may be employed in practicing my present invention. Figs. 4 and 5 illustrate other apparatus, also suitable for the purpose of my invention. 7o Figs. G and 7 are graphic representations of currents as used in the method hereinafter explained.

Referring to Fig. l, B and B indicate the secondaries of two transformers, each secondary being made in the manner commonly employed in electric metal-working apparatus, as a solid bar or mass of copper having a primary C or C applied in a groove in its side. A A are the laminated iron cores for 8o said transformers.

D D' D2 D3 are electrodes or contacts which are designed to pass heating-currents from the transformers into the work, here indicated at M as consisting of two strips of metal fed in the direction of the arrow between the electrodes or contacts. rlhe electrodes or contacts D' D3 are in the form of rollers and constitute pressure devices that will serve to unite the metal orotherwise op# 9o crate upon it as its heated portions pass between them. The two electrodes D D2 may be similarly constructed as rollers and one of them provided with a screw for pressing it firmly against the work.

' In using this apparatus, according to the old method, the heating-current was caused to pass through the section of metal included between the electrodes in the direction of the arrow from the pointwhere the contacts D ico D'2 bear to the point where the pressure devices D D3 bear, or to some point between my invention.

the pressure devices and the first-named contacts or rollers-that is to say, the current was passed in a longitudinal direction through the work before it reached the point where the pressure devi-ces were applied. lVhen the current is applied in this way, the work being drawn in the direction indicated by the arrows, the rollers D D2 being' forced toward each other slightly would effect the welding or otherwise act upon the heated metal. ln this operation the work has been found to heat principally between thc extremities of the secondaries or at the intermediate portion lying between the two sets of electrodes or contacts; but the parts of the work near the rollers would keep comparatively cool7 because of the fact that the rollers being of large mass and good conducting material would have a considerable cooling effect. Hence it frequently happened that by the time the heated work reached the point of application of the pressure devices it would becooled down so that the rollers could not act with the best effect.

It has also been proposed in some cases to pass the current transversely through the workhthat is to say, from contact D to D2, or reversely, and also from roller D to D2, or reversely. This would be effected by properly combining the transformers as to polarity so that they should work in series with one another. ln this method the work would heat at or near the contacts or electrodes; but the action was not satisfactory, because the partwhich would be heated between D and D2 would cool while passing to the pressure devices and would have to be reheated at the latter point in order that it might be welded or formed. Such aprocess would obviously be a wasteful one.

lily invention avoids the difliculties incident to the methods just explained and produces a uniform, effective and economical heating of the work.

In Fig. 3 I have illustrated apparatus which may be used for-the purpose of carrying out I have shown the secondaries of transformers as the source of the heatingcurrent, but do not limit myself to the employment of such instrumentalities.

In Fig. 3 l have shown practically two sets of transformers, one` consisting of secondaries B B', primaries C C, and cores A A', the other consisting of secondaries B2 B2, primaries G2 C3, and cores A2A3. The two secondaries B B2 on one side and B' B3 on the other are united in a single casting, but practically form each a separate secondary circuit. The contact-terminals of said secondaries are indicated at D D D2 D3 D4 D5. The terminal D serves as a common terminal for the two transformer secondaries B B2, and the terminal`D3 serves as a ccmmon terminal for the transformer secondaries B B3. Those terminals which are not employed for applying the pressure may be, as indicated, simple brushes, while those-to wit, D4 Dfiwhich are used .secondary B3.

for applying the welding' or forming pressure are rollers. By connecting' the primaries il and A to the source of energy in a manner to cause both poles or contacts D D2 in the respective secondaries to be of one sign and both poles or contacts D Dithercof to be of the opposite sign a current will flow in the work between the pointof application et' contacts D D2 and the point of application ef contacts D D2, the secondaries then supplying the current in multiple, and lthat poi-tien of the work extending from D D2 to D D serving to complete the circuit in the respective secoildaries. By connecting the primaries C2 C3 to the source of energy in a manner to cause the poles or contacts D D: of the respective secondaries to be of unlike sign and the poles or contacts DL D5 thereof le be of the reverse unlike signs respectivelyr the current will pass transversely through the strips, bars or rods constituting the wei-lt at the points of application of the contacts D', D2, DL and Dl-that is to say, current will V[low through the sccondaries in series including the portions of work between D and D and between D'and Di. As the work is supposed to be continually moving along', any pa rticular section will be first heated by the current passing longitudinally and then by the current passing transversely through it.

Fig. i illustrates practically the saine arrangement, with the exception that the two sets of transformers are entirelyseparate as to their secondaries, and an extra pair of contacts is therefore required. The arrows indicate'the directions of the current in the two systems. l

Fig. G graphically shows the necessary conditions of the current that two secondaries may be in series and heat the work transversely, as in the second heating described in connection with Figs. 3 and i. The full-lined curve may represent the waves of the alternating current in the secondary B2, Fig. 4, and the dotted curve the Waves of current in It will be seen that when the current in B2 is at a maximum and of positive sign, say, that in BJ is at Zero, but approaching its maximum negative sign, so that the two currents are in series, and the flow of currents as before mentioned. In order that the two currents may be in multiple, as in the longitudinal heating, the phases of current in each secondary must rise and fall simultaneously, or, in other words, coincide.

Fig. 5 illustrates apparatus wherein one secondary is made to provide the two heating' effects. Each secondary is providedl with two primary coils. B has the coils C and D2, and B the coils C and C2. C and U are connected in such lmanner that the secondary currents will be in multiple', and C2 C3 in such manner that Kthe secondary currents will be in series. Fach set of primaries is supplied from different sources of electric energy, one source being an alternating current having a greater frequency than the other. For instance, C C

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I 553,923 Y S is supplied with 'current from machine E and C2 C3 from machine Ijl. Suppose the current from E has a frequency that is greater than that of E, then the currents may be graphically shown as in Fig. 7. The dotted curve is the current E and the full curve that of E. It will be noticed that at certain points, as at Y, the two curves coincide, and the secondaries B B/ will supply current to the work in multiple. At some other instant the curves will be just opposed to each other and the currents of B B will be in series. At intermediatepoints a combination of effects will be produc-ed, which may be readily studied out from Fig. 7.

The arrows in 5 denote the direction of movement'of the Work.l

It `Will be obvious that, as. in the case .of

Figs. 3 and 4, the pressure-rolls, Fig. 5, might he made the terminal-s of the heating source,so

' that the current passed transversely through the Work would pass at the point of application of the pressure. It is also apparent that as the primaries furnishing longitudinal cur,-

rent are independent of those furnishing the transverse current, regulating devices may he used in each circuit to cause one or the other heating effect .to predominate. In Fig. 5, R and R are such regulating devices, .so that if it is desired to weld stock of large section'a heavier longitudinal current may he used Without increasing the transverse'current. Th us, for instance, the longitudinal current would' be increased when the thickness of the piece to be Welded Was increased, but

Where the width was not. This Would make a vheavier path for the longitudinalcurrent, but

the section of stock through which the transverse current iowed would he no greater. The length of the path through the work for thetransverse current might be slightlyT increased but Would be almost nothing as compared with the increased section for the longitudinal current; or, if the increase of thickness were attended by an increase of Width then the transverse current Would be increased in the proper ratio. Again if the Width of the stock was increased and the thickness correspondingly decreased in such ratio as to maintainl the saine area of crosssection transversely through the bar or 4hars to be heated thelongitudinal current would remain the same while the transverse current would need to be larger, as the cross-sectional area of the path would now be larger.

lVhat I claim as my invention is- In an, electric metal-Working apparatus, thecombination substantially as described with two transformers supplying heating-curv rents to the same Work, of alternating-current sources connectedl respectively to the primaries of said transformers, and adapted to supply alternating currents of dii-ferent frequency.

Signed at Lynn, inthe county of Essex and State of Massachusetts, this 12th day of June, 'A.'D.'1S91.

' HERMANN LEMP.

Witnesses: l C. A. WILKINSON,

NV. B; LEWIs. 

